Natural products, such as mushrooms, are generally picked individually and by hand, a very expensive procedure when current labor costs around the world are considered. As would be expected, as consumer demand for mushrooms and like food items has grown, considerable expense and effort has been expended in attempts to develop mechanical harvesting devices capable of reducing or even eliminating the necessity for manual involvement in the harvesting of the product. Such devices generally attempt to mechanize the actual picking of the product, as well as its subsequent transfer to a packing station. The problems which need to be overcome if successful mechanical harvesting of mushrooms or the like is to be achieved are many and are inherent in the mushroom growing process. Mushrooms are grown in rooms or enclosures where the desired environmental conditions of humidity, temperature, etc. are maintained, either naturally or artificially, in order to assist rapid growth of the mushrooms which is required for efficient production. Obviously, the maintaining of such conditions is not inexpensive and consequently, the plant equipment is arranged to fill the room or enclosure volume to the greatest possible extent commensurate with efficient production. Thus, mushrooms are grown commercially in trays or continuous beds containing the growing medium, such trays or beds being disposed in horizontal tiers separated vertically by a distance of only about 9-18 inches, being the minimum distance required to permit access to the mushrooms for harvesting using current methods. If the environmental conditions are maintained at optimum i.e. such that maximum growth is obtained, the mushrooms grow rapidly and frequently double or more in size in any given twenty-four hour period. Moreover, the mushrooms in any one bed or tray do not grow at an even rate. As a consequence, if mushrooms of uniform high quality are to be obtained, the mushrooms must be harvested at least on a daily basis. In fact, each bed must be harvested up to about four times if the optimum yield of high quality mushrooms is to be obtained. If harvesting is only effected once on each bed, i.e. all mushrooms are to be harvested at the same time, then both mature and non-mature mushrooms will be harvested with the result that many will be of lower quality and in any event, sorting of the mushrooms must be effected. Moreover, it must be borne in mind that the surface of the beds are not flat but undulate to some extent and mechanical harvesting devices to date have not been able to successfully take that fact into account manual. Manual harvesting operating is laborious and quite inefficient as will be appreciated when one considers that the beds or trays are some 4- 5 feet wide requiring a picker to lean over the bed for a large fraction of each work shift; and the distance between the beds or trays is only 9-18 inches; which is little room for even an experienced picker to effect the task of rapidly evaluating which mushrooms are of a mature quality and subsequently picking such mushrooms. Often, damage results to mushrooms which are immature and are left to be picked at a subsequent harvesting.
One attempt to harvest mushrooms mechanically is disclosed in U.S. Pat. No. 3,624,990 which describes a machine which includes a vibrating or rapidly oscillating elongated knife which cuts the stems of the mushrooms whilst a superimposed brush rotates with a forward movement of a carriage carrying the knife edge and holds the mushroom stems against the pressure of the knife blade. The brush subsequently pushes the cut mushrooms to a collecting belt conveyor which moves them to a collecting receptacle. The knife blade is of a length sufficient to extend over the full bed and consequently, harvest all of the mushrooms in one pass. The device, obviously, is totally non-discriminatory as regards the condition of individual articles being harvested. Special note may also be taken of the fact that the mushrooms are subjected to a relatively severe physical treatment by the brush member which can, and does, result in damaged product. A further apparatus for harvesting mushrooms is described in U.S. Pat. No. 3,970,150. This device was developed to be used in conjunction with a growing method in which an attempt is made to ensure that the mushrooms are grown in uniform rows and consequently are readily conducive to automatic harvesting. This procedure prima facie reduces the area of bed available for crop production, a very serious restriction when, as mentioned above, efficient production necessitates making the best use of all available growing area. The described apparatus is extremely complex and includes a number of pairs of members, each pair being arranged to lift up, individually, only mature mushrooms and, via a wheel arrangement, transfers same to a collection vessel. British specification No. 1336393 discloses a device for picking mushrooms which device includes a number of flexible nozzles each of which is in the form of a bellows-shaped body whose orifice fits over the head of each individual mushroom. Upon application of a vaccuum through the nozzles the bellows retract inwards and rotates and in doing so pull the mushrooms from the bed. A number of the said nozzles are included in a casing and the object is to manoeuvre the casing above a group of mushrooms, and so load all the bellows before bringing the loaded casing above a collecting basket. Obviously, this device leaves a lot to be desired, especially when one considers the unevenous of the beds and the difficulties in manoeuvering the casing. Another device which also utilizes a vacuum is disclosed in U.S. Pat. No. 3,635,005. This device is designed generally to be stationery; trays of mushrooms to be harvested are to be brought to the device and passed therethrough. As in the device as disclosed in U.S. Pat. No. 3,624,990, an elongated cutter blade is used which oscillates linearly across the bed, cut mushrooms are then blown via a number of air jets into collections means which consist of a large inlet to a mushroom collector vessel. A vacuum is continuously applied to the mushroom collector and consequently, through to the collecting conduit. In the mushroom collector, the entering mushrooms impinge upon a sponge member and subsequently drop into a receptacle. This device obviously is very cumbersome and could not be used in situ; i.e. on the mushroom beds located in their tier arrangement. This effectively would preclude its use in many modern plants, such as that of the present assignee, which utilizes continuous beds. Moreover, it is designed to be used in association with a mushroom crop containing relatively orderly rows of mushrooms--not the normal situation in most new commercial mushroom growing operations, and obviously there is no discrimination as to the maturity etc. of the mushrooms which are to be harvested. Also, the positive directing of a relatively large number of mushrooms simultaneously into and through the collecting housing to the mushroom collector leaves a lot to be desired as far as the delicate handling of the product is concerned. Moreover, presumedly the system has to be shut down to retrieve the mushrooms from the receptacle, yet another product handling stage and one which is not really commercially viable.
It is the object of the present invention to provide a mushroom harvester which can rapidly, continuously and most important selectively pick mushrooms from a growing bed and transfer the picked mushrooms from the bed to a packing station, or the like.
A further object is to provide such a device which is simple and relatively inexpensive to produce and can be extremely compact and hence be conveniently utilizable in the narrow space between growing beds.